T38Fax owns AS7324, and all of our services operate out of the 184.108.40.206/24 address block. Ports 5060 and 5080 are for SIP. Use of the non-standard port 5080 is recommended, and discussed in more detail here. The other ports mentioned are for RTP or UDPTL, the media streams. The SIP packets and RTP packets for a single session will often use different IP addresses.
220.127.116.11 UDP 5060, 5080, 35000-65000
18.104.22.168 UDP 5060, 5080, 35000-65000
22.214.171.124 UDP 5060, 5080, 35000-65000
126.96.36.199/30 UDP 16384-65000
188.8.131.52/26 UDP 16384-65000
Additionally, disabling the SIP ALG on the firewall may still be necessary in some cases.